MSNBC anchor Chris Matthews forcefully ripped into Sarah Palin’s advice that President Obama could “declare war on Iran” to improve his re-election chances, repeatedly calling her “frightening” and claiming she’s “an empty vessel” with “nothing going on mentally.”

Palin told Chris Wallace on Fox News Sunday that if Obama “played the war card” in that manner it “changes the dynamics in what we can assume is going to happen between now and three years.”

“She’s frightening. Mark, that is frightening stuff. Frightening,” Matthews said Tuesday on his show Hardball. “First of all, president don’t declare war. Anybody knows that in high school. Congress has to declare war. To declare war on Iran, I don’t think the most far right, Middle East hawk will talk about declaring war on Iran, a country with 70-some million people, with an advanced air force.

Speculating where her talking points are coming from, Matthews continued, “Why does she talk like that?… Is Michael Ledeen, a real hawk, writing this stuff for her? I don’t know anyone as far right as that, besides him.”

Matthews assailed her ostensible lack of knowledge on military matters and war, claiming she doesn’t understand the matter she’s discussing. “She has no idea what the Korean War was. She didn’t know anything,” he said.

Palin was the headline speaker at the Tea Party Convention in Nashville, Tennessee last weekend, where she assailed Obama and was caught peeking at notes on her hand.

Matthews took a direct swipe at her intellect, alleging that “she has nothing going on mentally.” Referring to her recent interview with Wallace, he said, “Nothing comes out. Nothing. She says nothing spontaneously when you ask her a serious question.”

Time magazine’s Mark Halperin agreed, saying Palin was “obviously flailing” during the interview.

Palin said Sunday she’s open to running for president in 2012 and that it would be “absurd” not to consider it.

“I’d be afraid of her,” Matthews continued. “She’s an empty vessel ready to be filled by ideology she does not understand, and that is really scary.”

Comparing her to former vice president Dan Quayle and former president George W. Bush, he added that “Nothing is more frightening than an empty vessel in power.”